Imprecise Tackiness

This week's message on the lighted ELCA church sign:

WORRY OFTEN GIVES SMALL THINGS A BIG SHADOW

And here I thought that was a trick of the light!

I know I shouldn't bother, but I keep trying to parse this logically. Is worry a source of light? If not, how can it give things a shadow? Might not shadows contribute to worry rather than vice versa?

I give up. I don't have time to puzzle this out, especially since I'm still stuck on Level 15 of Weffriddles.